1. Field of the Invention
The present invention relates to a pull cord stopper device for pleated blinds or Roman shades which are frequently raised or lowered.
2. Description of the Related Art
A conventional pull cord stopper device for use in a blind apparatus has been disclosed in Japanese Utility Model Application Hei-63-201199. The conventional pull cord stopper device according to this disclosure is mounted in a head box and is of a type that controls pull cords that are routed through the head box and extend out of one end of the head box.
The device according to this disclosure includes a stopper roller which is designed to maintain contact with the pull cords, where the stopper is rotatably supported by a guide member positioned on a floating axis which is perpendicular to a direction in which the the pull cords are routed. The device also includes a stopper case which supports the stopper roller and which has on its bottom surface a rotating contact face with the stopper roller. A loop-like guide groove is formed on the side walls of the stopper case above the rotating contact face. A stopper pin is disposed at a predetermined distance apart from the guide groove and between the side walls. Also provided is a restraint contact portion which is extended in parallel with the floating axis and which is radially apart from the guide member on the floating axis beyond the radius of the stopper roller. The restraint contact portion prevents the guide pin from sliding back in the loop guide in the stopper case. When a user exerts a force on the pull cords, the guide pin is caught by the restraint contact portion. When the force is removed after advancing the pull cords by some distance, the guide pin reverts back to its original position after one round of travel in the loop groove.
In the conventional pull cord stopper device, the width of the head box is subject to space limitations. When a large number of pull cords are used, some of the cords are stacked given the difficult to evenly space all the pull cords. In particular, when this occurs the pull cords are horizontally arranged across the width of the stopper device, thereby making it necessary to exploit the full width of the head box. Since the loop-like guide groove is formed on the side wall of the stopper case, the available inner width of the stopper case is limited. As a result, the number of the pull cords that can be used in a conventional device is limited. The loop-like guide groove formed on the side wall of the stopper case requires that the stopper case be high enough to accommodate the loop-like guide groove. The height of the stopper case is therefore required to be an undesirably large dimension.
The above problems may be resolved by allowing a slidable block to slide by means of the rotation of a pinch roller and a friction with the pull cords in order to suspend or release the pull cords. The pull cord stopper device of this type, however, also has certain problems--an aborted or insufficient travel of the slidable block, tangled pull cords, and an inevitable wear of the pull cords.